This invention relates to a method of detecting obstruction in the path of a moving closure, wherein a detection limit is set to identify obstructions at start-up.
Vehicle closures, such as windows, moonroofs, sunroofs, etc. are typically powered by a motor at the request of an operator closure switch. As the closure moves to close an opening in the vehicle cab, there may sometimes be an obstruction in the path of the closure. An obstruction, such as a passenger's arm, will increase the load on the motor closing the closure, or decrease the speed. Typically, a control system for the closure motor monitors a characteristic such as speed, power or torque, and identifies an obstruction should the monitored characteristic change more than a predetermined limit away from a predicted value.
Difficulties arise in setting the predicted value to correspond to the particular system dynamics for the closure in the vehicle. Further, other challenges, such as variations to the actual characteristic due to vibration, temperature, etc. may vary the monitored characteristic, for a reason other than obstruction.
To provide a more accurate indication of an obstruction, some systems have monitored the actual system response, and utilize that monitored system response as an indication of what the true predicted value should be. That is, some form of a "learn" cycle is utilized.
Closure systems typically monitor start-up changes. Typically, a start-up change would include a first upper peak, and then repeated decaying lower and upper peaks. However, a system that monitors start-up peaks, and utilizes the start-up peaks as "learned" expected value, will not always provide an accurate indication of an obstruction at start-up. That is, if an obstruction would give rise to a lower value than expected (such as a system monitoring speed) a lowered value at start-up might be seen as one of the valleys that follow the peak at start-up. Thus, there is the potential for missing an identification of an obstruction in a system which learns the system response and utilizes start-up values.